Dynamo-electric machine



Aug 28, 1923. 1,466,654

F. H. CLOUGH DYNAMO ELECTRIC MACHINE Filed Feb, 19, 1920 lnVentor I F'reder-ic H. Cloggh, y flhwq. h

His Attorney.

near Rugby,

Patented Aug. 28, 1923.

UNITED STATES PATENT OFFICE.

FREDERIC H. CLO'UG'H, 0F HIIJLMORTON, NEAR RUGBY, ENGLAND, ASSIG-NOR TO- GENERAL ELECTRIC COMPANY, A. CORPORATION OF NEW YORK.

DYNAMIC-ELECTRIC MACHINE.

Application filed February 19, 1920. Serial No. 359,879.

To all whom it may concern:

Be it known that I, FREDERIC HORTON CLoUGH, a subject of the King of Great Britain, residing at Hillcrest, Hillmorton, in the county of IVarwickshire, England, have invented certain new and useful Improvements in Dynamo-Electric Machine-s, of which the following is a clear and exact description, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in dynamo electricmachines and more particularly to the small type of generator which it has become customary to provide on selfpropelled vehicles for supplying current for lighting the vehicle and also in some cases for starting the engine. As these machines are driven at greatly varying speeds difiio culties have arisen n connection with the generator into and out 5 in the shunt field mechanism for controlling the voltage of the current supplied and also for connecting the of circuit when the speed rises above or falls below a predetermined minimum.

It has hitherto been proposed in connec tion with this type of generator to provide what is known as a trembling contact voltage regulator in which a non-inductive resistance connected in series with the shunt field winding of the generator is normally short circuited by a pair of contacts but when the voltage rises beyond a predetermined amount, a small electromagnet connected across the main terminals separates these contacts for a short interval of time and the current passes through the non-inductive resistance and field in series with the result that the exciting field is reduced and the voltage lowered. When the voltage is lowered the pull of the electromagnet is no longer sufficient to keep the contacts apart and one of these contacts, vibrates, thus producing a rapidly varying current winding, the average value of which is sufiicient to maintain the proper voltage of the generator.

One of the difiiculties which sometimes arises in connection with a device of this type is that the contacts become dirty and their engaging surfaces pitted or in some cases they may even be fused together so that the operation may become unreliable. An object of the present invention is toprovide of the machine brushes 3 and 4.

apparatus for the purpose set forth which shall be rugged in construction and reliable in action. In a preferred embodiment I secure one of the contacts to a rotating memer which may conveniently be the armature and arrange the vibrating contact so that it engages this rotatin con tact. A feature of this arrangement'is that when the vibratory contact comes into enpolished and cleaned and the reliability of operation creased.

In carrying this part of my invention into effect I prefer to utilize the commutator of the machine as the rotating contact, but It is to be understood that a slip ring or other contact carried by the armature shaft The vibratory contact of a solenoid which the dynamo exceeds a predetermined amount raises the contact off the commutator and thereby connects the non-inductive resistance in series with the shunt field thereby reducing the voltage. When the voltage is sufficiently reduced the contact again engages the commutator thereby short circuiting the resistance.

This invention further consists in. providing means for connecting the dynamo in circuit when its speed rises above a predetermined minimum. This may be accomplished by attaching one of the brushes to a spring controlled lever which is *operated by a solenoid so that the main circuit will not be supplied with current until the voltage of the generator has risen sufliciently to enable the solenoid to pull the brush into engagement. with the commutator against the action of the controlling spring.

In the accompanying drawing, Fig. 1 diagrammatically illustrates a preferred embodiment of my invention and Figs. 2 and 3 diagrammatically illustrate modifications of ,this embodiment.

In thedrawing 1 represents the commutator of the generator which is engaged by the main The contact 2 is under the control of solenoid 5 which when energized owing to the voltage of the generator exceeding a predetermined value raises the contact 2 off the commutator and thereby inserts a non-inductive resistance 6 in series a vibratory contact 2 and by with the shunt field 7 of the generator thereby reducing the exciting field and lowering the generator voltage. When the voltage drops below the predetermined value the controlling spring 8 overcomes the pull or the solenoid 5 so that it again engages the commutator and short-circuits the resistance 6, until the voltage rises again when the solenoid Will again overcome the spring.

To connect the generator in circuit I preferably provide a novel form of automatic switch. In this construction the brush 3 is mounted on a lever 9 controlled by a spring 10. This lever is also under the control of a solenoid 11 so arranged that the main circuit is not supplied with current until the current energizing the solenoid is sufiicient to ovencome the pull .of the spring 10. The solenoid 1.1 is provided with a. winding 12 connected across the main circuit and a winding 13 connected in series with the main circuit. Therefore, when the brush 3 is out of engagement with the commutator 1, the resistance 6 is connected in series with both of the windings 5 and 12.

At low speeds of the machine the vibratory contact 2 of the voltage controller will be in engagement with the commutator thereby completing a circuit through the shunt field 7. So long as the brush 3 is held in its off position by its controlling spring 10 the circuit through the solenoid 5 for operating the vibratory contact will contain the field regulating resistance and the voltage therefore which the vibrating contact will tend to maintain will be higher than it would be after the dynamo brush 3 is lowered. This ensures that there will be sufficient voltage (6 operate the solenoid 11 and close the main circuit before the solenoid 5 commences to operate to maintain constant voltage. After the main circuit is closed by the lowering of the brush 3 on to the commutator, the solenoid 5 is connected across the main terminals and so tends to maintain the desired voltage. By this time a certain amount of current will be passing through the main circuit and the current in coil 13 of solenoid 11 together with the current in coil 12 will be sufiicient to keep the brush 3 in contact with the commutator thereby maintaining the main circuit closed.

in the modification shown solenoid 11 controls both the main brush 3 and the vibrating contact 2. it will be evident that since the solenoid 1,1 is provided with both series and shuntwindings, the vibrating contact controls both the voltage and the current in a suitable manner.

In the modification shown in Fig. 3. the vibrating contact is adapted to engage a slip ring 15 carried by the armature shaft instead of engaging the commutator 1 as shown in Figs. 1 and The slip 15) in Fig. 2, the

is electrically connected to a brush 16 on the commutator 1 by any suitable means such as a brush 17 and a conductor 18.

lVhile l have shown and described several modifications of my invention, I do not desire to be limited to the specific arrangements shown but seek to cover in the appended claims all those modifications which fall within the true spirit and scope of my invention.

Having thus described my invention, what I claim as new and desire to secure by Let-' ters-Patcnt is:

l. The combination in a generator having a rotor and a stator, of" a voltage regulator including an annular contact means carried by said rotor and coaxial therewith, a cooperating vibratory contact and a voltage coil energized from said generator for causing vibration of the latter.

2. The combination in a generator having a rotor and a stator, collectors, and an annular member carried by said rotor "for delivering current to said collectors, of a regulator including a vibratory contact coacting with said annular member, and a solenoid energized from said generator for causing vibration of said contact.

3. The combination in a generator having a stator and a rotor, the latter carrying a commutator, of a voltage regulator including a vibratory contact coacting with said commutator and an actuating coil for said contact connected to said generator to derive therefrom current of a voltage substantially proportional to that of said genorator.

i. The combination in a generator of an armature and a field, a resistance adapted to be placed in series with said field, a short circuit for said resistance, and a switch adapted to connect said generator across a load circuit, said switch also controlling said short circuit.

5. In combination, a variable speed direct current generator having a shunt field winding, a resistance adapted to be connected in series with said field winding, an automatic switch adapted when closed to connect said generator to a load circuit, an operating coil for said switch connected in series with said resistance across the terminals of said generator when said switch is open, and con-- nections whereby said operating coil is connected across the terminals of said generator independently of said resistance when said automatic switch is closed.

6. In combination, a variable speed direct current generator having an exciting winding. a resistance adapted to be connected in series with said exciting winding, an automatic switch, means ior operating said switch, a voltage regulator coil connected in series with said rer .ance across the terminals of said generator when said switch open, and connections whereby said regulator coil is connected across the terminals of generator independently of said re sistance when said automatic switch is closed.

In combination, a variable speed direct current generator having a shunt field winding a resistance adapted to be connected in series with said field winding, an automatic switch adapted when closed to connect said generator to a load circuit, a voltage regulator coil connected in series with said resistance across the terminals of said generator when said switch is open and controlling a short circuit around said resistance when said automatic switch is closed, and connections whereby said regulator coil is connected across the terminals of said generator independently of said resistance when said automatic switch is closed.

In combination, a variable speed direct current generator having a shunt field Wind regulator coil connected in series with said is closed.

In testimony whereof I have signed my name to this specification this 16th day 01 January 1920.

FRED. H. GLOUGH.

Witnesses:

JOHN HALFORD, DOROTHY WHITE. 

